Bull S.a.

Jean Perraudeau

Jacques Abily

A Process for coherent management of exchanges between memories in an information system having at least two levels of memories. The information system in one embodiment is constituted by a central subsystem which can communicate with one or more peripheral subsystems by means of input-output units. The central subsystem includes several processors linked to a central memory and to the input-output units. Each processor includes an associated cache memory linked with the central memory. In operation, each processor executes the instructions of programs contained in an associated cache memory. If the cache memory does not contain the data necessary to the associated processor, the data is read in the central memory and a copy is made using memory blocks of predetermined size. The coherent management of exchange between memories is achieved by dynamically applying a management mode selected as a function of the use that is made of each block. The management mode, either update or invalidate mode, is switched based upon a predetermined threshold of ineffectiveness for a particular mode being reached. Furthermore, soft misses can be a criteria for the ineffectiveness of the invalidation mode.

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Paris, France

Jean Perraudeau